Triangle defined by g.f.: Sum_{n>=0} (4*n)!/n!^4 * x^(2*n)*y^n/(1-x-x*y)^(4*n+1), read by rows.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =26a(5) =1a(6) =1a(7) =123a(8) =123a(9) =1a(10) =1a(11) =364a(12) =3246a(13) =364a(14) =1a(15) =1a(16) =845a(17) =25210a(18) =25210a(19) =845a(20) =1a(21) =1a(22) =1686a(23) =120135a(24) =606500a(25) =120135a(26) =1686a(27) =1a(28) =1a(29) =3031